■各ブラウザのコーデックサポート状況

https://en.wikipedia.org/wiki/HTML5_video#Browser_support

●H.265/HEVC
・https://html5test.com/compare/feature/video.codecs.mp4.h265.html
・https://caniuse.com/#feat=hevc

●VP9
・https://html5test.com/compare/feature/video.codecs.webm.vp9.html
・https://caniuse.com/#feat=webm

●AV1
・https://caniuse.com/#feat=av1